music-functions: problem with -\tag

[Nicolas Sceaux]

Hello,

While working on ly/music-functions-init.ly, I had a little problem
with the \tag keyword, when occuring after a '-':

  c1-\mytag #'part ^4
  
the parser complains:

/home/nicolas/lilypond-cvs/dev/tag-filter.ly:28:12: Erreur: syntax error, 
unexpected MUSIC_FUNCTION_SCM_MUSIC:
    c1-\myta
            g #'part ^4

I am not sure where/how to change the parser so that scheme music
functions could be accepted at that place. Perhaps in the 'post_event'
rule?

nicolas